Optical lenses have long been used to manipulate light for various advantages. Fresnel lenses, for example, are used in lighthouses to bend light from all angles of a point light source into a beam or beams. Fresnel lenses are one particular type of blazed grating. More recently, micro-diffraction gratings have been utilized in holographic and augmented/virtual reality (AR & VR) devices.
One particular AR & VR device is a wearable display system, such as a headset or head mounted display operable to display an image within a short distance from a human eye. The image can be a computer generated image on a display, such as a micro display. The optical components are arranged to transport light of the desired image, generated on the display to the user's eye to make the image visible to the user. The image generated can form part of a light engine, wherein the image itself generates collimated light beams guided by the optical component to provide an image visible to the user.
Different kinds of optical components have been used to convey the image from the display to the human eye. These optical components include lenses, mirrors, optical waveguides, holograms and diffraction gratings, or slanted gratings. Slanted gratings are one particular type of blazed gratings, and may be used for AR & VR systems, such as wearable display systems, displays on mobile devices, etc., wherein the functional design relies on efficient light input and/or output coupling from the grating to the viewer's field of view.
While the manufacture of binary gratings with vertical walls is known, existing techniques for producing slanted gratings fail to achieve adequate grating uniformity, fin shaping, and angle control. Therefore, with respect to these and other drawbacks the present disclosure is provided.